The sound of a cracking knee isn't particularly pleasant. But it gets worse when you listen up close. "It does for most people. But for me,it just makes me excited." Omer Inan, an electrical engineer at Georgia Tech."I actually feel like there's some real information in them that can be exploited for the purposes of helping people with rehab."

这段话引起了文章的主题，向我们介绍了即使a cracking knee发出的声音让很多人感觉不舒服，但对于Georgia却认为这些声音富含很多信息，并且可以为患者康复提供信息。

因此这段话可以概括为：

The sound of a cracking knee provides real information which can help people with rehab.

Inan's experience with cracking knees goes back to his days as an undergrad at Stanford, where he threw discuss. "If I had a really hard workout, then the next day of course I'd be sore, but I'd also sometimes feel this catching or popping or creaking every now and then in my knee."

第二段讲述了Inan曾经扔铁饼的经历来讲述自身运动之后膝盖出现的问题。

这段话总体来说只是一个背景的介绍，这对于retell lecture这个题型来说，这段的信息其实是不重要的。即使在听录音，记笔记的过程中我们记到了这点，在最后十秒钟的准备时间中，我们可以有效地把这个信息点删除。

A few years later, he found himself building tiny microphones at ahigh-end audio company. So when he got to Georgia Tech and heard the Defense Advanced Research Projects Agency, DARPA, wanted better tech for knee injuries, he thought: Why not strap tiny microphones to people's knees, to eavesdrop as their legs bend? "What we think it is, is the cartilage and bone rubbingagainst each other, the surfaces inside the knee rubbing against each other,during the movements."

这一段详细解释了Iana希望把tinymicrophone插入膝伤患者的膝盖，通过“窃听”在移动过程中膝盖发出的声音，来检测膝伤患者的情况。

因此这段话可以概括为：

He wants to strap a tiny microphone which he found at a high-end audio company to better understand the knee injuries.

He and a team of physiologists and engineers built a prototype withstretchy athletic tape and a few tiny mics and skin sensors. And preliminarytests on athletes suggest the squishy sounds the device picks up are moreerratic, and more irregular, in an injured knee than in a healthy one. WhichInan says might allow patients and doctors to track healing after surgery.Details appear in the IEEE Transactions on Biomedical Engineering.

这段描述了两个关键信息点：

1. 他和他的team通过使用可延展的运动绷带，一个微型mics和皮肤传感器制作了一个模型。实验表明比起健康的膝盖，受伤的膝盖所传出的声音更加的不稳定，不寻常。

2. 这个发现 可以让患者及医生有效的追踪手术后的恢复情况。

因此这段话可以概括为：

·        By using tape, tiny mics and skin sensors, sounds from injured kneeis more erratic and irregular than healthy one.

·        Thus, patients and doctors might use it to track healing aftersurgery.

"The primary application we're targeting at first is to give people a decision aid during rehabilitation, following an acute knee injury, to help them understand when they can perform particular activities, and when they can move to different intensities of particular activities." A usefulthing to take a crack at.

这段话主要讲的是其的具体应用。在人们遭受严重给人们一些康复建议。让他们明白什么时候可以从事哪些不同强度的活动。

因此这段话可以概括为：

It can give people adecision aid during rehabilitation after knee injury, including what activities can they involve and when they can move to different densities of activities.

总结一下这篇retell lecture主要说了以下几点：

·       The sound of a cracking knee provides real information which can help people with rehab.

·       He wants to strap a tinymicrophone which he found at a high-end audio company to better understand the knee injuries.

·       By using tape, tiny mics and skin sensors, sounds from injured knee is more erratic and irregular than healthy one.

·         Thus, patients and doctors might use it to track healing after surgery.

·      It can give people a decision aid during rehabilitation after knee injury, including what activities can they involve and when they can move to different densities of activities.